<?php

$array = ['sum','sub','mul','div'];
shuffle($array);
echo $function = $array[0];

echo $function(10,2);
echo "\n\n";

function sum($a=0, $b=0) {
  return $a+$b;
}

function sub($a=0, $b=0) {
  return $a-$b;
}

function mul($a=0, $b=1) {
  return $a*$b;
}

function div($a=0, $b=1) {
  return $a/$b;
}
